Field of Invention
The present invention relates to a printed circuit board package structure and a manufacturing method thereof.
Description of Related Art
Generally speaking, in the manufacturing process of a printed circuit board, a specific element, such as a copper block for heat dissipation, a core, etc., needs to be placed into a preset accommodation recess of the printed circuit board. The core, being magnetic, can be used in a transformer structure or a power choke structure.
In a conventional printed circuit board having a four-layered package structure, a copper clad laminate (CCL) is used as a substrate. When the printed circuit board is manufactured, a forming machine can be utilized to form a plurality of ring-shaped accommodation recesses not communicated with each other on the front surface of the substrate. Then, ring-shaped cores are placed into the accommodation recesses and epoxy is filled in the accommodation recesses to fix the cores. After that, glass fibers (FR4) having copper foils on their surfaces can be laminated to the front surface and back surface of the substrate followed by processes such as drilling, copper electroplating, and the like, to form vias that conduct the copper foils on the front surface and the back surface of the substrate. Finally, the copper foils are patterned and the front surface and the back surface of the substrate are covered by epoxy.
When the forming machine forms the accommodation recesses on the substrate, the cutting tool must first be moved downwardly to touch the substrate, then moved horizontally to cut and form the ring-shaped accommodation recess. After one accommodation recess is formed, the cutting tool is lifted to move above the location on the substrate where the next accommodation recess is expected to be formed. The aforementioned steps are repeated to form plural accommodation recesses on the substrate, such that lots of time is spent on vertical movements (ascent and descent) of the cutting tool.
In addition, the adhesive in the accommodation recesses will generate stress after being cured, which leads to reduce inductance value of the cores. In addition to that, although the adhesive may have a heat dissipation function, the gas in the accommodation recesses may still expand due to the high temperature in the infrared reflow (IR reflow) oven when surface mount technology (SMT) process is performed on the printed circuit board. As a result, pressure cannot be released to possibly damage the glass fibers and the epoxy that covers the substrate.